I think the March announcement indeed is the 70D. I also think it will be the first camera with Canons new 180 nm process at around 24 mp and single Digic 5 for modest FPS. Wifi and GPS is a given, especially if it is 60D build. I think it will get a variant of 6D AF also for good low light photos and video.
I think 7D2 will also have a new sensor with same 180 nm process, but stay at 18 mp to be the FPS/Hi-ISO monster we all want. Basically a crop 1DX.
The reason for this is for Canon to put out the new sensor in a lower prestige body to get feedback for final spec of 7D2 before they announce it. It also gives the 7D2 a longer time as "latest and greatest crop body", as if the higher mp XXD is release after, it would pull down 7D2 prices. But if released before, the 7D2 lower mp can be marketed as "better", and as a consequence, will not be as sensitive for the next XXD upgrade, as that will certainly have even higher mp count.